The maximum power and efficiency that an internal combustion engine is capable of is limited by knock. This can occur when gasses during the compression stroke reach a temperature and pressure where they spontaneously combust. Cooling the combustion gasses allows higher pressures & hence power and efficiency.
Another problem that exists in internal combustion engines, particularly those that are air-cooled, stems from the fact that rich mixtures are used to cool cylinder heads and or exhaust system to improve durability. This approach to cooling not only increases fuel consumption but it also increases the output of environmentally troublesome emissions. At maximum power with heads of this invention it is not necessary to operate with rich mixtures for cooling or to avoid knock.
In air and liquid cooled engines alike, the combination of cyclical thermal stresses and reduced material properties are causal factors leading to cracking. These cracks often occur between the inlet and outlet valves seats or spark plug holes. This area is generally the hottest temperature surrounding the combustion chamber, and in prior art heads often exceeds 475° F. At this temperature aluminums tensile and yield strength is half of what it is at 320° F. The heads of the present invention do not exceed 320 F.
In some prior art engines, including diesel engines, inadequate cooling of the heads produce warping that can interfere with the sealing necessary between the heads and cylinder block.
In the case of liquid cool automotive engines, the head and cylinder block are sealed by a gasket. This requires that the cylinder block be provided with a thick plate like top surface called a deck. The heads are likewise provided with a thick plate like structure adjacent to the combustion chamber. Between these two plate structures the gasket is squeezed to seal water and combustion gasses. These thick plate like structures are in the high temperature areas of the head, significantly reducing heat transfer from the combustion chamber and piston rings into the coolant.
Another problem that occurs in engines is when thermal expansion of the head produces excessive stress on the studs used to secure the head to the crankcase. Excessive stresses on these studs can cause distortion of cylinder bores and cracks in the crankcase. This is particularly true when the case is made of aluminum and/or magnesium.
Another problem is that the valves, ports and spark plugs reduce the area of contact between the coolant and combustion chamber. This is particularly true in cases where 4 or 5 valves per cylinder are used. As will be explained later, the intent of the present invention is to increase the surface area of contact between the coolant and combustion chamber by creating a skirt around the perimeter of the combustion chamber. In the preferred embodiment said skirt extends downward to encompass the piston and rings.
My objectives are to solve all of these problems.
It will become apparent to those skills in the art to which this invention relates how the problems listed above are solved by my invention.
These and still other objects and advantages of the invention will become apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiments taken with the accompanying drawings.